Page 114 - Introduction to Petroleum Engineering

ACTIVITIES 99
A. What is residual oil saturation (S )?
orw
B. What is connate water saturation (S )?
wc
C. What is the relative permeability to oil at connate water saturation k (S )?
ro
wc
D. What is the relative permeability to water at residual oil saturation k (S )?
orw
rw
E. Assume oil viscosity is 1.30 cp and water viscosity is 0.80 cp. Calculate
mobility ratio for water displacing oil in an oil–water system using the
data in the table and mobility ratio = λ Displacing λ / displaced = (k rw (S orw µ / ) w / )
(
(kS wc )/µ o ).
ro
5.6 A well is producing oil in a field with 20‐acre well spacing. The oil has vis-
cosity 2.3 cp and formation volume factor 1.25 RB/STB. The net thickness of
the reservoir is 30 ft and the effective permeability is 100 md. The well radius is
4.5 in. and the well has skin = 0. What is the productivity index (PI) of the well
in STB/D/psi?
5.7 A. Interfacial tension (IFT) σ can be estimated using the Weinaug–Katz vari-
ation of the Macleod–Sugden correlation:

N c N c  ρ ρ 
/
σ 14 = ∑ i 14 = ∑ chi  x i L − y i V 
σ
/
P
= i 1 = i 1  M L M V 
where σ is the interfacial tension (dyne/cm), P is an empirical parameter
ch i
known as the parachor of component i [(dynes/cm) /(g/cm )], M is the
3
1/4
L
molecular weight of liquid phase, M is the molecular weight of vapor
V
phase, ρ is the liquid phase density (g/cm ), ρ is the vapor phase density
3
V
L
3
(g/cm ), x is the mole fraction of component i in liquid phase, and y is the
i
i
mole fraction of component i in vapor phase. The parachor of component
i can be estimated using the molecular weight M of component i and the
i
empirical regression equation (Fanchi, 1990):
+
.
.
P = 10 02 92 M i
chi
This procedure works reasonably well for molecular weights ranging from
100 to 500. Estimate the parachor for octane. The molecular weight of
+
=
octane (C H ) is approximately 8 12 18 1 114, and the density of
*
*
18
8
octane in the liquid state is approximately 0.7 g/cc.
B. Estimate the contribution σ of IFT for octane in a liquid mixture with
i
density 0.63 g/cc and molecular weight 104. Assume there is no octane in
the vapor phase and the mole fraction of octane in the liquid phase is 0.9.